Acyl compounds are usually derived from a corresponding carboxylic acid by removal of one (or more) hydroxyl groups. The 'acyl' compound contains the R-C=O group where R represents an organyl (organic substituent with at least one free valence electron at a carbon atom) or, in the case of methanoic (formic) acid, an H.

All acyl compounds contain the carbonyl functional group.

Examples of acyl compounds

Remember, for derivatives of methanoic acid, the R group will be H.